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Subject: Re: [OMPI users] Allgather in inter-communicator bug,
From: Battalgazi YILDIRIM (yildirimga_at_[hidden])
Date: 2010-05-20 11:48:40


Hi,

you are right, I should have provided C++ and Fortran example, so I am doing
now

Here is "cplusplus.cpp"

#include <mpi.h>
#include <iostream>
using namespace std;
int main()
{
    MPI::Init();
    char command[] = "./a.out";
    MPI::Info info;
    MPI::Intercomm child = MPI::COMM_WORLD.Spawn(command, NULL, 8,info, 0);
    int a[8]={0,0,0,0,0,0,0,0};
    int dummy;
    child.Allgather(&dummy, 0, MPI::INT, a, 1, MPI::INT);
    child.Disconnect();
    cout << "a[";
    for ( int i = 0; i < 7; i++ )
        cout << a[i] << ",";
    cout << a[7] << "]" << endl;

    MPI::Finalize();
}

Here is again "fortran.f90"

program main
 use mpi
 implicit none
 integer :: parent, rank, val, dummy, ierr
 call MPI_Init(ierr)
 call MPI_Comm_get_parent(parent, ierr)
 call MPI_Comm_rank(parent, rank, ierr)
 val = rank + 1
 call MPI_Allgather(val, 1, MPI_INTEGER, &
                    dummy, 0, MPI_INTEGER, &
                    parent, ierr)
 call MPI_Comm_disconnect(parent, ierr)
 call MPI_Finalize(ierr)
end program main

here is how you build and run

-bash-3.2$ mpif90 fortran.f90
-bash-3.2$ mpiCC -o parent cplusplus.cpp
-bash-3.2$ ./parent
a[0,0,0,0,0,0,0,0]

If I use mpich2,
-bash-3.2$ mpif90 fortran.f90
-bash-3.2$ mpiCC -o parent cplusplus.cpp
-bash-3.2$ ./parent
a[1,2,3,4,5,6,7,8]

I hope that you can repeat this problem to see problem with OPENMPI,

Thanks,

On Thu, May 20, 2010 at 10:09 AM, Jeff Squyres <jsquyres_at_[hidden]> wrote:

> Can you send us an all-C or all-Fortran example that shows the problem?
>
> We don't have easy access to test through the python bindings. ...ok, I
> admit it, it's laziness on my part. :-) But having a pure Open MPI test
> app would also remove some possible variables and possible sources of error.
>
>
> On May 20, 2010, at 9:43 AM, Battalgazi YILDIRIM wrote:
>
> > Hi Jody,
> >
> > I think that it is correct, you can test this example in your desktop,
> >
> > thanks,
> >
> > On Thu, May 20, 2010 at 3:18 AM, jody <jody.xha_at_[hidden]> wrote:
> > Hi
> > I am really no python expert, but it looks to me as if you were
> > gathering arrays filled with zeroes:
> > a = array('i', [0]) * n
> >
> > Shouldn't this line be
> > a = array('i', [r])*n
> > where r is the rank of the process?
> >
> > Jody
> >
> >
> > On Thu, May 20, 2010 at 12:00 AM, Battalgazi YILDIRIM
> > <yildirimga_at_[hidden]> wrote:
> > > Hi,
> > >
> > >
> > > I am trying to use intercommunicator ::Allgather between two child
> process.
> > > I have fortran and Python code,
> > > I am using mpi4py for python. It seems that ::Allgather is not working
> > > properly in my desktop.
> > >
> > > I have contacted first mpi4py developers (Lisandro Dalcin), he
> simplified
> > > my problem and provided two example files (python.py and fortran.f90,
> > > please see below).
> > >
> > > We tried with different MPI vendors, the following example worked
> correclty(
> > > it means the final print out should be array('i', [1, 2, 3, 4, 5, 6, 7,
> 8])
> > > )
> > >
> > > However, it is not giving correct answer in my two desktop (Redhat and
> > > ubuntu) both
> > > using OPENMPI
> > >
> > > Could yo look at this problem please?
> > >
> > > If you want to follow our discussion before you, you can go to
> following
> > > link:
> > >
> http://groups.google.com/group/mpi4py/browse_thread/thread/c17c660ae56ff97e
> > >
> > > yildirim_at_memosa:~/python_intercomm$ more python.py
> > > from mpi4py import MPI
> > > from array import array
> > > import os
> > >
> > > progr = os.path.abspath('a.out')
> > > child = MPI.COMM_WORLD.Spawn(progr,[], 8)
> > > n = child.remote_size
> > > a = array('i', [0]) * n
> > > child.Allgather([None,MPI.INT],[a,MPI.INT])
> > > child.Disconnect()
> > > print a
> > >
> > > yildirim_at_memosa:~/python_intercomm$ more fortran.f90
> > > program main
> > > use mpi
> > > implicit none
> > > integer :: parent, rank, val, dummy, ierr
> > > call MPI_Init(ierr)
> > > call MPI_Comm_get_parent(parent, ierr)
> > > call MPI_Comm_rank(parent, rank, ierr)
> > > val = rank + 1
> > > call MPI_Allgather(val, 1, MPI_INTEGER, &
> > > dummy, 0, MPI_INTEGER, &
> > > parent, ierr)
> > > call MPI_Comm_disconnect(parent, ierr)
> > > call MPI_Finalize(ierr)
> > > end program main
> > >
> > > yildirim_at_memosa:~/python_intercomm$ mpif90 fortran.f90
> > >
> > > yildirim_at_memosa:~/python_intercomm$ python python.py
> > > array('i', [0, 0, 0, 0, 0, 0, 0, 0])
> > >
> > >
> > > --
> > > B. Gazi YILDIRIM
> > >
> > > _______________________________________________
> > > users mailing list
> > > users_at_[hidden]
> > > http://www.open-mpi.org/mailman/listinfo.cgi/users
> > >
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >
> >
> >
> > --
> > B. Gazi YILDIRIM
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
>
>
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>

-- 
B. Gazi YILDIRIM